Chart for determining exposures.



A. D. SHLAND.

CHART FOR DETERMINING EXPOSURES.

APPLICATION FILED SEPT. 7, 1915'.

ARTHUR D. SHILAND, OF CLEVELAND, OHIO.

CHART FOR DETERMINING EXPOSURES.

Sp.ecication of Letters Patent.

Patented Feb. 15, 1916.

Application filed September 7, 1915. Serial No. 49,277.

To all whom it may concern Be it known that I, ARTHUR D. SHILAND, acitizen of the United States, and a resident of Cleveland, in the countyof Cuyahoga and State of Chio, have invented certain new and usefulImprovements in Charts for Detei-mining Exposures, of which I herebydeclare the following to be a full, clear, and exact description, suchas will enable others skilled in the art to` which it appertains to makeand use the same.

The invention relates to means for ascertaining the proper position ofthe diaphragm in a photographic camera and the amount of time ofexposure of the sensitized plate or film to the light while taking aphotograph.

The objects of the invention are to provide a simple and efcient form ofexposure chart or scale suitable to the use of amateurs and by means ofwhich the correct amount of time for exposing a sensitized plate or filmto the light can be ascertained,` at a glance for any condition ordegree of intensity of the light values, and for any characteristic ofthe subject and its proximity to the operator, and also the amount ofopening of the diaphragm for any character or subject and condition oflight values.

rIhe invention comprises a chart or scale for ascertaining the aboveenumerated features and includes, series of spaced horizontal andvertical lines crossing each other upon the chart and providingpositions cor responding with which are placed the indicating names ofgraduated values of light corresponding with peculiar characteristics ofthe subject and vice versa, which are read upon adjacent sides of thechart, and includes also similarly indicated graduated relative valuesof time to the amount of diaphragm opening, and which are placed uponopposite adjacent sides of the chart. By means of diagonals intersectingwith the intersecting points of the aforesaid lines and dividing theminto as many parts as may be required, the proper relative values oftime of exposure and amounts of diaphragm opening can be ascertainedwhen the relative values of light and characteristic qualities of thesubject are known.

The invention further includes means for determining the proper relativecombina tions to be read upon the scale orchart for varying angles ofinclination of the sun above the horizon during the day.

. divisions of the Further means are provided for indicating the mannerof reading the chart or scale for varying rates of speed capability ofthe sensitized plate or film used at any time. The chart indicating afixed or normal condition for plates or films capable of being affectedat ordinary speeds, also a means is provided for modifying the readingto obtain correct values of time of exposure for varying periods of theyear.

The invention includes the features of novelty and utility hereinafterdescribed, shown in the accompanying drawings and specifically pointedout in the claims.

In the accompanying drawings the ligure illustrates by means of aprinted scale the features and manner of arrangement of the severalvalues for immediate comparison.

In the drawing a chart is formed of vertical lines X, X and horizontallines y, y, intersecting therewith, separating the body of the chartinto horizontal and perpendicular spaces and these spaces' areintersected by diagonal lines Z, Z, crossing the intersecing points ofthe horizontal vertical lines. Upon the left side of the ligure thusformed are disclosed graded subject characteristics and numbered 1 to 11inclusive, arranged opposite horizontal lines, such as the following:

Landscape near or{Dark average distance. Light Distant landscape. 9

Seashore or snow i: 10 Distant sea and clouds 11 described subjects areindicated opposite the` vertical lines at the top ofthe chart ingraduated order, as follows:

A Intense B Very bright C Bright D Faint shadow E Dull F Very dull Theamount of opening for the diaphragm. in relation to time isdistinguished at the bottom of the chart opposite the verticafL lines inparts of' focal system at U. S. and F respectively, in focal length ofthe lens, F.

U. S. standard and the 1' sun may be indicated 45- 32-22-16-11.3-8-5.6*4 2.8 hIl. S. l28-32 16*8`42-1,` and the length oftime exposure -is indicated at the right of the chart in seconds andfractions thereof opposite the horizontal lines as 2 2/3-2-,-1/3-1-2/3*1/2 1/3 1/4 1/6 1/8- U12*1/17-1/25`1/e7`1/5o 1/75- l/lOO, etc.

In employing this chart the characteris-v tics of subject and light arefirst considered as indicated upon the diagram or chart. For instance ifa dark landscape is to be photographer upon a bright day, the procedureis as follows: Following thel horizontal line opposite the words Darklandscape (6) on the chart. it is followed until it intersects with thevertical line C opposite the word Bright for a corresponding lightvalue. At this intersection the diagonal line 4 will be found and thisdiagonal line will be the index for exposure value. After the diagonalline 4 is found and if a time of exposure of 1,/25 of a second isdesired to be used, the diagonal line is followed until it intersectswith the horizontal line opposite l/25 in the time column, and thevertical line intersecting at the same point is followed downward to 8U. S. in the column of diaphragm openings and will indicate that 8 U. S.standard is the amount of opening required in the diaphragm and thecamera adjustments are accordingly set therefor. In this light are giventhe amount of opening for the diaphragm can be obtained for any time ofexposure desired, or if the amount of diaphragm opening is predeterminedat U. S. 4 the time of exposure can be determined by following theyvertical line upward till it intersects with the diagonal line 4, andthen following the horizontal line intersecting therewith and the timeof exposure for that amount of opening will be found to be l/50 of asecond.

The modifications for reading the chart at the various degrees ofinclination of the by adding a number orfraction to the index number ofthe ascertained diagonal line. That is, if the time should be late inthe day or early in the morning, in the example given the numeral lshould be added to 4 and the number of the diagonal line to be followedwill be 5 to obtain correct time exposure and amount of diaphraglnopening. A separate diagram may be made on the chart to show the changesfor sun elevation above the. horizon, as at l/V. For a speedy or fastplate a fraction as l/2 can be subtracted from the numeral of thedetermined diagonal line manner when the subject and' zontal lines,

and for a slow plate a fraction as 1,/2 can be added to the numeral ofthe diagonal line. For the several calendar months of the year numeralscan be added to advance the diagonal line to correspond with reducedlight values. f

This scale will read directly for substantially all photographs taken inoutdoor work by amateurs without the use of the' correcting features. jl

Having described the invention what I claim as new and desire to secureby Letters Patent is:

l. In a chart for determining the time of exposure and amount of openingof the diaphragm, of a camera shutter, a series of subjectcharacteristics and horizontal lines, coinciding respectively therewith,and a se-l ries of light values and vertical lines coincidingrespectively therewith and intersecting said horizontal lines, incombination with a series of time values corresponding respectively withthe horizontal lines and a series of widths of diaphragm openingscorresponding respectively with said vertical lines, vand paralleldiagonal lines intersecting with the intersections of the horizontal andyertical lines for determining the correct time values relative toamounts of diaphragm opening when considered with predetermined subjectmatter and sight conditions specified upon the horizontal and verticallines.

2. In a chart for determining the time of exposure and amount ofdiaphragm opening to be used with predetermined subject matter and lightcondition, a series of horizontal lines coinciding respectively with thedescription of subject matter, a series of vertical lines 'coincidingrespectively with 100 the descriptionof light conditions, 4and a seriesof parallel diagonal lines intersecting the intersections of saidvertical and horiand a series of time values coinciding with saidhorizontal lines and a se- 105 ries of amounts of diaphragm openingcorresponding with said vertical lines, each diagonal line beingfollowed to its intersection with the horizontal line corresponding withthe desired time of exposure, and

thence the vertical line intersecting therewith and withv saidhorizontal line being followed to one of the series of amounts ofdiaphragm openings.

In testimony whereof, I hereunto set my hand this 26th day of Aug. 1915.l

ARTHUR D. SHIIJAND. In presence of-A RALPH W. JEREMIAH, WM. M. MoNRoE.

